History Main / MassiveMultiplayerCrossover

* The [=MetLife=] insurance company has released an [[https://www.youtube.com/watch?v=0blgtGvrz0A ad]] featuring characters from "Peanuts," "Looney Tunes," Hanna-Barbera, and many other animation studios.

* A [=MasterCard=] commercial featured several food mascots (from Count Chocula to the Pillsbury Doughboy) eating dinner -- with Mr. Clean doing the dishes.

* The Met Life insurance company has released an ad featuring characters from "Peanuts," "Looney Tunes," Hanna-Barbera, and many other animation studios.

* ''Anime/IsekaiQuartet'' is a comedic take with TrappedInAnotherWorld works from Kadokawa Corporation, featuring the casts from ''[[LightNovel/KonoSuba KonoSuba: God's Blessing in this Wonderful World!]]'', ''[[LightNovel/Overlord2012 Overlord]]'', ''[[LightNovel/ReZero Re:Zero - Starting Life in Another World]]'', and ''[[LightNovel/YoujoSenki The Saga of Tanya the Evil]]'' being transported to another world... To attend high school in a chibi style. Season 2 also adds the protagonists of ''LightNovel/TheRisingOfTheShieldHero'' as part of the secondary cast, with characters from ''[[LightNovel/TheHeroIsOverpoweredButOverlyCautious Cautious Hero: The Hero Is Overpowered but Overly Cautious]]'' appearing as cameos.

** Later on when faced with Uwe Boll's ''Film/AloneInTheDark2005'', the Nostalgia Critic gave up on reviewing it. Until! [[WebVideo/TheSpoonyExperiment Spoony]] and [[WebVideo/AtopTheFourthWall Linkara]] arrived to assist him.

* ''Anime/IsekaiQuartet'' is a comedic take with TrappedInAnotherWorld works from Kadokawa Corporation, featuring the casts from ''[[LightNovel/KonoSuba KonoSuba: God's Blessing in this Wonderful World!]]'', ''[[LightNovel/Overlord2012 Overlord]]'', ''[[LightNovel/ReZero Re:Zero - Starting Life in Another World]]'', and ''[[LightNovel/YoujoSenki The Saga of Tanya the Evil]]'' being transported to another world... To attend high school in a chibi style. Season 2 also adds the protagonis of ''LightNovel/TheRisingOfTheShieldHero'' as part of the secondary cast, with characters from ''[[LightNovel/TheHeroIsOverpoweredButOverlyCautious Cautious Hero: The Hero Is Overpowered but Overly Cautious]]'' appearing as cameos.

This trope has become increasingly common in video games, especially those involving both licensed and original properties. These games, depending on how far or how deep they mine, can have interesting effects on the fiction chosen. Many long-gone and/or forgotten HumongousMecha shows, for example, often get a new lease on life, or even a brand-new sequel or remake, after making an appearance or two in a ''VideoGame/SuperRobotWars'' game. Similarly, the ''Franchise/FireEmblem'' series was finally brought over to the US to great success after two of its characters made an appearance as unlockable fighters in ''VideoGame/SuperSmashBrosMelee''. Crossing over in RealLife, {{Racing Game}}s with licensed vehicles (such as VideoGame/{{Forza}}, VideoGame/GranTurismo, VideoGame/NeedForSpeed) are always this trope, due to the fact multiples of vehicles are licensed from wildly different manufacturers for use in-game.

This trope has become increasingly common in video games, especially those involving both licensed and original properties. These games, depending on how far or how deep they mine, can have interesting effects on the fiction chosen. Many long-gone and/or forgotten HumongousMecha shows, for example, often get a new lease on life, or even a brand-new sequel or remake, after making an appearance or two in a ''VideoGame/SuperRobotWars'' game. Similarly, the ''Franchise/FireEmblem'' series was finally brought over to the US to great success after two of its characters made an appearance as unlockable fighters in ''VideoGame/SuperSmashBrosMelee''.

* [[https://www.youtube.com/watch?v=0HF4NgVkpjE&t=1138s "Multiverse"]] An hour long fan edit of ''Film/AvengersEndgame'' adding in an insane number of fandoms including ''Film/Shrek'', ''Franchise/StarWars'', ''Franchise/StarTrek'', ''Manga/OnePunchMan'' and ''Creator/ChuckNorris'' just to name a few.

* A 2019 ad for Walmart's pickup service featured a plethora of pop culture cars from the [[Franchise/{{Batman}} Batmobile]], [[Film/{{Ghostbusters}} Ecto 1]], K*I*T*T* from ''Series/KnightRider'', a [[Film/JurassicPark Ford Explorer]], [[WesternAnimation/{{Cars}} Lightning McQueen]], the [[Film/{{DumbAndDumber}} Mutts Cutz van]], the [[Film/NationalLampoonsVacation Griswold family station wagon]], and many, many more.

* ''Once Upon A Multiverse'' is based on this concept, doing for fiction what ''Series/OnceUponATime'' did for fairy tales. The main cast ''alone'' pulls from ''ComicBook/{{Firestorm}}'', ''Manga/MobPsycho100'', ''Anime/KillLaKill'', ''VideoGame/FireEmblemGenealogyOfTheHolyWar'', ''WesternAnimation/SuperFriends'', ''VideoGame/HalfLife'', ''VideoGame/{{Undertale}}'', ''Manga/TheOnesWithin'', ''VideoGame/{{Mafia}}'', ''VideoGame/SpidermanPS4'', ''Anime/DragonBallZ'', and ''WesternAnimation/StevenUniverse''. That's not even getting into the supporting cast.

* A 2019 ad for Walmart's pickup service featured a plethora of pop culture cars from the [[Franchise/{{Batman}} Batmobile]], [[Film/{{Ghostbusters}} Ecto 1]], K*I*T*T* from ''Series/KnightRider'', a [[Film/JurassicPark Ford Explorer]], [[Film/{{Cars}} Lightning McQueen]], the [[Film/{{DumbAndDumber}} Mutts Cutz van]], the [[Film/NationalLampoonsVacation Griswold family station wagon]], and many, many more.

* ''Once Upon A Multiverse'' is based on this concept, doing for fiction what ''Series/OnceUponATime'' did for fairy tales. The main cast ''alone'' pulls from ''ComicBook/{{Firestorm}}'', ''Manga/MobPsycho100'', ''Anime/KillLaKill'', ''VideoGame/FireEmblemGenealogyOfTheHolyWar'', ''WesternAnimation/SuperFriends'', ''VideoGame/HalfLife'', ''VideoGame/{{Undertale}}'', ''Manga/TheOnesWithin'', ''VideoGame/{{Mafia}}'', ''VideoGame/SpidermanPS4'', and ''Anime/DragonBallZ''. That's not even getting into the supporting cast.

* ''Once Upon A Multiverse'' is based on this concept, doing for fiction what ''Series/OnceUponATime'' did for fairy tales. The main cast ''alone'' pulls from ''ComicBook/{{Firestorm}}'', ''Manga/MobPsycho100'', ''Anime/KillLaKill'', ''VideoGame/FireEmblemGenealogyOfTheHolyWar'', ''WesternAnimation/SuperFriends'', ''VideoGame/HalfLife'', ''VideoGame/{{Undertale}}'', ''Manga/TheOnesWithin'', ''VideoGame/{{Mafia}}'', and ''VideoGame/SpidermanPS4''. That's not even getting into the supporting cast.

* The [[TheFilmOfTheBook adaptation]] of ''Literature/ReadyPlayerOne'', that this to [[UpToEleven a new level]] of craziness.

* The [[TheFilmOfTheBook adaptation]] of Literature/ReadyPlayerOne, that this to [[UpToEleven a new level]] of craziness.

* In 2019, in the Comics and Cartoons board of [[Website/FourChan 4chan]] webcomic named [[https://the-conservatory.fandom.com/wiki/Let%27s_Make_A_Comic! Let's Make a Comic!]] was released, which was the result of many comments building a story.

* In 2019, in the Comics and Cartoons board of ''Website/4Chan'', a webcomic named [[https://the-conservatory.fandom.com/wiki/Let%27s_Make_A_Comic! Let's Make a Comic!]] which was the result of many comments building a story.

* In 2019, in the Comics and Cartoons board of Website/4chan, a webcomic named [[https://the-conservatory.fandom.com/wiki/Let%27s_Make_A_Comic! Let's Make a Comic!]] which was the result of many comments building a story.

* In 2019, in the Comics and Cartoons board of ''Website/4chan'', a webcomic named [[https://the-conservatory.fandom.com/wiki/Let%27s_Make_A_Comic! Let's Make a Comic!]] which was the result of many comments building a story.

* ''Disney/WreckItRalph'' does this with arcade video game characters.
** In ''Disney/RalphBreaksTheInternet'', Vanellope is sent to the website Oh My Disney, where she meets all the Franchise/{{Disney Princess}}es (and inspires them to wear comfortable clothes). The site is also populated with characters from subsidiaries Creator/{{Pixar}}, Creator/{{Lucasfilm}} and Creator/MarvelStudios.

* ''The Search For Mickey Mouse'' was a [[WhatCouldHaveBeen scrapped]] Creator/{{Disney}} film from the early 2000s meant to coincide with WesternAnimation/MickeyMouse's 75th anniversary. In it Mickey gets kidnapped. WesternAnimation/{{Goofy}}, WesternAnimation/DonaldDuck, and Basil from ''Disney/TheGreatMouseDetective'' go around the world looking for him and encountering numerous Franchise/DisneyAnimatedCanon characters. The film was inspired by cut scenes from ''Film/WhoFramedRogerRabbit'' and ''Disney/{{Fantasia 2000}}''. Rumors existed that the film was coming out as late as 2012. The film however was cancelled all the way in 2002. The team couldn't figure out how to make an engaging film with a decent plot that also involved Disney cameos every few scenes. A more successful crossover involving Disney IP's would eventually materialize in the form of the Oh My Disney sequence in ''Ralph Breaks the Internet'' (see above).

** On top of that, the casts of then-running shows introduced the performances of the night in-character. Among the more surreal ones were [[Theatre/SpiderManTurnOffTheDark a chorus of Spider-Men]] introducing the revival of ''Annie'', the ''Theatre/RockOfAges'' cast introducing ''Cinderella'' and [[Disney/TheLionKing Mufasa and Simba]] introducing the Pippin revival.

* ''WebAnimation/TheFrolloShow'', made by [[Creator/{{chincherrinas}} the same creator]] of ''WebAnimation/SmashBrosLawl'', is also this, with characters from various media such as [[Disney/TheHunchbackOfNotreDame Frollo]], [[Disney/BeautyAndTheBeast Gaston]], [[Anime/PantyAndStockingWithGarterbelt Panty and Stocking]], and other cartoon, anime, film, and video game characters (see [[Characters/TheFrolloShow here]] for more). Unlike most examples, it eventually starts developing an interesting plot and deeper interactions between all the characters.

* The early-90s [[VerySpecialEpisode public service announcement]] ''WesternAnimation/CartoonAllStarsToTheRescue'' had characters like the ''WesternAnimation/{{Teenage Mutant Ninja Turtles|1987}}'', ''WesternAnimation/TheSmurfs'', ''[[Disney/TheManyAdventuresOfWinnieThePooh Winnie the Pooh]]'', the cast of ''WesternAnimation/DuckTales1987'', and many others team up to teach a single kid about the dangers of drugs [[spoiler: and save his sister from same]]. Although, if you can see Smurfs, there's a good chance you're tripping balls already.

Read to a child commercial

* The Arabic TV channel Spacetoon produced a play that crossed over ''Anime/{{Pokemon}}'' and ''Manga/DetectiveConan''. [[NotMakingThisUpDisclaimer No seriously]], [[https://www.youtube.com/watch?v=rVzXIWz1zgY they did]].